A fuel injection valve of this kind has been disclosed by DE 197 27 896.5, filed Jul. 1, 1997, which and contains a valve member, which is supported so that it can move bidirectionally and can control the opening and closing of a fuel outlet opening. Actuating means are provided, which can move the valve member in order to open and close the fuel outlet opening. In this instance, the actuating means include an electrically actuatable control valve and a discharge pressure chamber, which on the one hand xe2x80x94via a connection that can be opened and closed by the control valvexe2x80x94communicates with a closing pressure chamber and on the other hand communicates with a relatively pressure-free fuel tank. The closing pressure chamber is defined on one end by a closing pressure surface embodied on the valve member and communicates with a high-pressure fuel source, via a throttle, wherein the pressure in the closing pressure chamber against the closing pressure surface generates a closing force, which engages the valve member. When the control valve is closed, the pressure in the closing pressure chamber produces a closing force of sufficient magnitude to hold the valve member in its closed position. When the control valve is opened, a pressure drop occurs in the closing pressure chamber since more fuel can escape into the discharge pressure chamber through the open connection that can flow into the closing pressure chamber via the throttle. This results in the fact that the closing force generated by the pressure in the closing pressure chamber is reduced until the opening forces engaging the valve member predominate and the valve member executes an opening stroke.
When the valve member is disposed in its closed position, a sealing zone of the valve member cooperates with a valve seat in such a way that a surface area section of the valve member in the sealing zone or downstream of the sealing zone is decoupled from the high pressure prevailing upstream of the sealing zone. As soon as an opening stroke of the valve member lifts the sealing zone up from the valve seat, the high pressure can also build up downstream of the sealing zone since less fuel can escape through the fuel outlet opening than flows into the high-pressure fuel source through the connection that is now open. This results in the fact that during the opening stroke of the valve member, the high pressure also prevails against the above-mentioned surface area section downstream of the sealing zone and introduces an additional opening force onto the valve member. In order to reduce the influence of these additional dynamic opening forces on the adjusting movement of the valve member and consequently on the control behavior of the fuel injection valve, the known fuel injection valve has compensation means which can exert compensation forces on the valve member which counteract an opening stroke of the valve member. In the known fuel injection valve, these compensation means have a piston, which is supported so that it can move in an associated cylinder. At one end, the piston defines a hydraulic chamber in the cylinder, which is acted on with a reference pressure, in particular the pressure of the high-pressure fuel source. At the other end, the piston is supported in a starting position against a stop that is stationary in relation to the cylinder; via force transmission means, the valve member can drive the piston out of its starting position, which moves it away from its stop. In the known fuel injection valve, the force transmission means are constituted by an additional hydraulic chamber which is defined on one end by the piston and is defined on the other end by a compensation pressure surface embodied on the valve member. With an opening stroke of the valve member, therefore, a pressure can build up in this additional hydraulic chamber of the force transmission means, which rapidly increases to a maximum value, but then remains constant because the position of the piston can change starting at this maximum pressure value, so that the volume in the additional hydraulic chamber remains constant. As a result, a stabilizing compensation force on the valve member is produced, which evens out the opening process of the fuel injection valve member and improves the controllability of the fuel injection valve. The functioning of this compensation means, particularly during the closing of the valve member, thus depends on the leakage occurring and the rigidity of the hydraulic medium, in particular fuel, being used for the transmission of force, which can have a particularly powerful effect at high injection pressures.
It is a principal object of the invention, to provide a fuel injection valve in which the compensation forces, particularly their dependence on the opening stroke of the valve member, can be more precisely predetermined since the elasticities or rigidities of the springs used can be predetermined with a high degree of precision. In addition, an increased functional reliability can be assured for the closing process of the valve member since spring means operate independently of leakages.